The homeless man was lying on the ground, shaking, when police arrived early Wednesday. His face was soaked, apparently with urine, his nose broken, his chest and arms battered.

Police said two brothers from South Boston ambushed the 58-year-old as he slept outside of a Dorchester MBTA stop, and targeted him because he is Hispanic. One of the brothers said he was inspired in part by GOP presidential candidate Donald Trump.

The allegations ignited widespread condemnation Wednesday.

Mayor Martin J. Walsh said the brothers “should be ashamed of themselves.” Boston’s top prosecutor, Daniel F. Conley, called the case “sickening.”

Police Commissioner William B. Evans, a South Boston resident, said the brothers had given his neighborhood “a bad name.” He called it “a disgrace.”

Trump, told of the alleged assault, said “it would be a shame . . . I will say that people who are following me are very passionate. They love this country and they want this country to be great again. They are passionate.”

Trump, in his campaign kickoff speech in June, made disparaging comments about Mexican immigrants that advocates feared could cause a backlash against immigrants.

In Dorchester District Court on Wednesday, Scott and Steve Leader, who have extensive criminal records, pleaded not guilty to multiple assault charges with a dangerous weapon, indecent exposure, and making threats. The men stayed behind a half-open door during their court hearing to avoid cameras; their lawyers declined to comment on the charges against them.

Steve Leader is also charged with malicious destruction of property over $250 after he allegedly punched and kicked a cell door at the State Police barracks in South Boston.

Judge Lisa A. Grant ordered the men held without bail.

During the proceedings, Suffolk Assistant District Attorney Andrew Kettlewell described the attack as “vicious and unprovoked.”